An electrical storage unit (for example, see Patent Literatures 1 and 2) including a plurality of electrical storage elements such as secondary batteries and large-capacity capacitors has been widely used to store and discharge electric power as necessary.
The conventional art of the electrical storage unit will be described below with reference to the accompanying drawings.
FIG. 7 is an exploded perspective view showing the overall structure of the electrical storage unit according to the related art. The electrical storage unit is a battery pack disclosed by Patent Literature 1. In the battery pack, as shown in FIG. 7, a plurality of batteries 101 are stacked by a spacer 103. Further, positive and negative electrodes are provided on two ends of the battery 101, and the batteries 101 are arranged such that the adjoining positive and negative electrodes are opposite to each other.
To the electrodes of the batteries 101 arranged in two layers by the spacer 103, a plurality of battery lead plates 105 are electrically connected. Thus, the batteries 101 are connected in series-parallel.
Out of the batteries 101 configured thus, the batteries 101 in the lower layer are contained along guide grooves 109 provided in a lid case 107. At this point, the batteries 101 are fixed by double-sided adhesive tape (not shown) attached to the guide grooves 109.
The lid case 107 is covered with a body case 111 over the batteries 101. A circuit board 115 is placed on the top surface of the body case 111 via a board holder 113. A plurality of output leads 117 are electrically connected to the circuit board 115, and the output leads are electrically connected to connection terminals 119 integrally formed on the battery lead plates 105.
In this configuration, the batteries 101 are stacked to eliminate a redundant space, resulting in a size reduction, and parts of the side surfaces of the batteries 101 are fixed to the lid case 107 with the double-sided adhesive tape, so that a battery pack excellent in resistance to vibrations can be realized.